Warm-season Perennial Grass Research Articles

157 Microbial inoculant effects on limpograss silage

Abstract Warm-season perennial grasses are the main forage sources preserved as silage or haylage by livestock producers in subtropical and tropical regions; however, the nutritive value and silage fermentation parameters are often less than desirable. Microbial inoculants have been used to improve grass silage nutritive value and fermentation characteristics with inconsistent results. The objective of this study was to investigate the effects of a microbial inoculant on nutritive value and fermentation parameters of ‘Gibtuck’ limpograss (Hemarthria altissima) silage. Treatments were silage treated with SiloSolve FC (68.1 billion CFU/g, Lactobacillus lactis and Lactobacillus buchneri) or control (no microbial inoculant) distributed in a complete randomized design with 10 replicates. The inoculant level used was 0.5 g/Mg of forage. The experiment was conducted in Ona, FL in May 2023. Twenty 4 × 4 m plots of established limpograss were harvested at 15-cm stubble height with 58-d regrowth interval. The forage was chopped to a particle size ranging from 10 to 18 mm, placed into mini-silos (PVC pipes with rubber), and sealed immediately. The inoculant was applied with a hand sprayer before ensiling. The silos were opened after 60 d for analysis. There was no difference (P > 0.05) between the inoculant and control treatments on DM concentration (25%), DM recovery (96%), NDF (67%), and NFC concentrations (14%); however, silage treated with inoculant had greater CP (8.5 vs. 8.0%; P = 0.03), IVTD (56 vs. 54%; P = 0.01), and NDFD (53 vs. 51%, P = 0.02) and lesser ADF concentrations (38 vs. 40%; P = 0.02) than control. The inoculant did not affect (P > 0.05) silage pH (4.2) and lactic acid concentrations (1.5%) but resulted in greater acetic acid (2.5 vs. 2.0%; P = 0.01), propionic acid (1.6 vs. 1.0%, P < 0.01), and total acid concentrations (5.6 vs. 5.0%; P = 0.04), and decreased butyric acid (0 vs. 0.2%; P < 0.01), isobutyric acid (0.1 vs. 0.4%; P < 0.01), and NH3-N concentrations (4.4 vs. 5.3% N; P < 0.01). Aerobic stability (140 h), mold (1.1 log cfu/g) and yeast (2.2 log cfu/g) count were not affected (P > 0.05) by the inoculant treatment. At the genus level, there was no difference (P > 0.05) in relative abundance of Lactobacillus (85%), Enterobacter (4.0%), Enterococcus (1.8%), and Weissella (0.2%) between inoculant and control, but silage treated with inoculant had less Clostridium (1.0 vs. 2.3%, P = 0.04), Pediococcus (0.2 vs. 0.3%, P = 0.03) and greater relative abundance of Lactococcus (2.8 vs. 0.5%, P < 0.01) and Bacillus (0.2 vs. 0.1%, P = 0.01). At the species level, the inoculant was effective to increase the relative abundance of Lactococcus lactis (from 0.02 to 0.48, P = 0.002) and Lactobacillus buchneri (from 1.4 to 1.9, P = 0.03). SiloSolve FC is a promising microbial inoculant to be used in warm-season grass silage in subtropical and tropical regions.

Flowering Periods, Seed Yield Components, Seed Quality, and Patterns of Seed Shattering in Paspalum: Effect of Taxonomy and Nitrogen Fertilization.

Perennial warm-season grasses typically have reduced seed yield, making it essential to identify the critical seed yield components. An induced increase in nitrogen could help determine which components are most limiting. This research aimed to estimate seed yield components in Paspalum; evaluate N fertilization effects on the reproductive phase, seed yield components, and seed quality; and establish the pattern of seed shattering over time. Nine genotypes covering different reproductive periods were used. The experimental design was a randomized complete block design in a split-plot arrangement with three replications. The main plots had two nitrogen levels (0 and 150 Kg N ha-1), and the sub-plots contained different genotypes. Seed yield variation was mainly related to reproductive tiller density among germplasm with different flowering periods. Early-flowering germplasm showed an extended flowering period (159%), greater tiller density (27.7%), greater reproductive tiller density (157%), and higher yield (302%) in response to nitrogen fertilization. Seed-quality traits and seed retention were not affected by nitrogen fertilization. Seed retention over time followed an inverted sigmoid pattern, though there was considerable variation among taxonomic groups. Early-flowering germplasm exhibited superior seed retention. Seed yield in Paspalum is mainly influenced by the density of reproductive tillers and seed retention.

Limpograss [Hemarthria altissima] Silage and Protein Supplementation as an Alternative Feed Option for Growing Heifers in North Florida.

Limpograss (Hemarthria altissima) is a warm-season perennial grass that has the potential to feed livestock during scarcity periods. This study evaluated the intake, nutrient digestibility, and animal performance of beef heifers fed 'Gibtuck' limpograss silage combined with different levels of a range cube supplementation. Twenty-four heifers (330 ± 16 kg live weight) were submitted to four different treatments with 6 replicates: (1) control, no supplementation + limpograss silage ad libitum; (2) 1.4 kg of supplement + limpograss silage ad libitum; (3) 2.8 kg of supplement + limpograss silage ad libitum; and (4) 4.2 kg of supplement + limpograss silage ad libitum. The apparent total tract digestibility of dry matter, organic matter, and crude protein showed a positive quadratic effect with increasing supplementation levels (p = 0.001, p = 0.002, and p < 0.0001, respectively). Overall, the supplement improved diet digestibility and total DM intake but reduced silage intake, indicating a combined effect (substitutive and additive effect) of the protein supplement. The increasing level of protein supplement increased the average daily gain with a quadratic effect (p ≤ 0.0001). Limpograss silage associated with supplementation can improve diet digestibility and increase the animal performance of growing heifers, providing an alternative for livestock in North Florida.

133 Effects of supplementing corn silage to fall-calving heifers and cows grazing bermudagrass on cow and calf performance and physiology

Abstract The objective was to test the effect of supplemental feeding of corn silage to cows grazing bermudagrass pastures on cow and calf performance and physiology. In a completely randomized design, multiparous and primiparous Angus-crossbred cows (n = 24) grazed bermudagrass pastures assigned to one of two levels of supplemental feeding (non-supplemented or supplemented at 1% of BW on a DM basis of corn silage) during the growing season. Each replicate (pasture, n = 4 per treatment) was stocked with 3 cows. Cows averaged 155 ± 14 d of gestation at trial initiation. Cows were fed corn silage (38% DM, 7.83% CP DM basis) daily in fenceline bunks, and supplementation rate was adjusted throughout the trial to maintain 1% of BW. Cows were weighed on two consecutive days at both initiation and conclusion of the trial and cows were maintained on similar diets for 4 d prior to collecting weights to minimize variation in ruminal fill. Body weight (BW), body condition score (BCS), hair score (HS), hair length (HL), and rump fat (RF) measurements were collected at initiation (the middle of the second trimester), trial mid-point (beginning of third trimester), and approximately 2 wk before estimated parturition. Cows were removed from experimental pastures upon trial conclusion and relocated to calving pastures consisting of tame grasses (&amp;gt;65% bermudagrass). Data were analyzed as a mixed model with pasture as experimental unit and cows within pasture as subsamples. Cows began the trial at an average BW of 549 ± 22 kg (SEM) and an average BCS of 5.2 ± 0.17 (SEM). Supplementation of second and third trimester pregnant cows on bermudagrass did not influence BW gain, BCS, HS, or HL (P &amp;gt; 0.27). Rump fat tended (P = 0.15) to be increased with supplemental feeding. Supplemental feeding of corn silage on warm season perennial grass during the growing season did not appear to impact late gestation cow performance at the level fed in this study.

83 Effects of cottonseed meal supplementation on growth performance of heifers grazing mature summer forage

Abstract As perennial warm-season grasses mature in late summer, dry matter intake (DMI) of growing heifers may be limited due to low protein (7.2 ± 2.5 %) and increased NDF content (67.5 ± 2.7%), which may compromise growth potential. Cottonseed meal (CSM) supplementation may improve forage digestibility by increasing rumen degradable protein offered, but research regarding the specific effects of CSM supplementation on gain performance and composition of gain in heifers is limited. It was hypothesized that supplementation of CSM to heifers grazing mature forage would have greater growth performance compared with heifers not receiving CSM. Objectives for this experiment were to compare the effects of two CSM supplementation strategies on the growth performance of heifers grazing mature summer forage. In two consecutive summers, commercial Angus cross heifers (n = 63) weighing 266.08 ± 32.74 kg were blocked by BW (light, medium, and heavy) and allocated to 9 paddocks (1.64 ha) of WW-B. Dahl Bluestem (Bothriochloa bladhii) for 67 to 70 d. This was a RCBD with a factorial arrangement of 3 treatments by 3 BW blocks, with paddock and year as random effects. Heifers received one of three supplementation strategies: no cottonseed meal (CON), 454 g/animal of CSM daily (CSM1), or 908 g/animal of CSM every other day (CSM2). Initial and final shrunk BW were measured; ADG and percent of BW gained were calculated. Ultrasound of initial and final longissimus muscle area (LMA), backfat (BF), and intramuscular fat (IMF) were measured; percent gained was calculated, respectively. There were no treatment by block interactions for any measured variable. Heifers receiving CSM1 and CSM2 had greater final BW than heifers receiving CON (317 and 320.8 vs 302.6 kg, respectively; (P = 0.01). Likewise, percent of BW gained was greater (P = 0.02) for CSM1 and CSM2 supplemented heifers compared with CON heifers (19.4 and 20.2 vs 14.6%, respectively). The ADG of CSM1 and CSM2 supplemented heifers was greater (P = 0.01) than CON (0.74 and 0.78 vs 0.54 kg/d, respectively). Treatment did not affect the percent of BF (P = 0.24) or IMF gained (P = 0.39). Heifers receiving CSM1 and CSM2 tended to gain proportionally more LMA than heifers receiving CON (13.58 and 13.77 % vs 7.24%, respectively; P = 0.07). As anticipated, BW block affected final BW (P &amp;lt; 0.001) and percent BW gained (P = 0.02), as well as percent LMA gained (P = 0.02). In conclusion, CSM supplementation significantly affected growth performance of heifers grazing late summer WW-B. Dahl Bluestem forage versus no supplementation. In addition, there was no difference in growth performance between heifers receiving 454 g/d of CSM supplementation or 908 g/animal every other day, indicating flexibility for feeding strategy.

Genome-wide profiling of histone (H3) lysine 4 (K4) tri-methylation (me3) under drought, heat, and combined stresses in switchgrass

BackgroundSwitchgrass (Panicum virgatum L.) is a warm-season perennial (C4) grass identified as an important biofuel crop in the United States. It is well adapted to the marginal environment where heat and moisture stresses predominantly affect crop growth. However, the underlying molecular mechanisms associated with heat and drought stress tolerance still need to be fully understood in switchgrass. The methylation of H3K4 is often associated with transcriptional activation of genes, including stress-responsive. Therefore, this study aimed to analyze genome-wide histone H3K4-tri-methylation in switchgrass under heat, drought, and combined stress.ResultsIn total, ~ 1.3 million H3K4me3 peaks were identified in this study using SICER. Among them, 7,342; 6,510; and 8,536 peaks responded under drought (DT), drought and heat (DTHT), and heat (HT) stresses, respectively. Most DT and DTHT peaks spanned 0 to + 2000 bases from the transcription start site [TSS]. By comparing differentially marked peaks with RNA-Seq data, we identified peaks associated with genes: 155 DT-responsive peaks with 118 DT-responsive genes, 121 DTHT-responsive peaks with 110 DTHT-responsive genes, and 175 HT-responsive peaks with 136 HT-responsive genes. We have identified various transcription factors involved in DT, DTHT, and HT stresses. Gene Ontology analysis using the AgriGO revealed that most genes belonged to biological processes. Most annotated peaks belonged to metabolite interconversion, RNA metabolism, transporter, protein modifying, defense/immunity, membrane traffic protein, transmembrane signal receptor, and transcriptional regulator protein families. Further, we identified significant peaks associated with TFs, hormones, signaling, fatty acid and carbohydrate metabolism, and secondary metabolites. qRT-PCR analysis revealed the relative expressions of six abiotic stress-responsive genes (transketolase, chromatin remodeling factor-CDH3, fatty-acid desaturase A, transmembrane protein 14C, beta-amylase 1, and integrase-type DNA binding protein genes) that were significantly (P < 0.05) marked during drought, heat, and combined stresses by comparing stress-induced against un-stressed and input controls.ConclusionOur study provides a comprehensive and reproducible epigenomic analysis of drought, heat, and combined stress responses in switchgrass. Significant enrichment of H3K4me3 peaks downstream of the TSS of protein-coding genes was observed. In addition, the cost-effective experimental design, modified ChIP-Seq approach, and analyses presented here can serve as a prototype for other non-model plant species for conducting stress studies.

Genome-Wide Identification and Characterization of the TIFY Gene Family and Their Expression Patterns in Response to MeJA and Aluminum Stress in Centipedegrass (Eremochloa ophiuroides)

The TIFY family is a group of novel plant-specific transcription factors involved in plant development, signal transduction, and responses to stress and hormones. TIFY genes have been found and functionally characterized in a number of plant species. However, there is no information about this family in warm-season grass plants. The current study identified 24 TIFY genes in Eremochloa ophiuroides, a well-known perennial warm-season grass species with a high tolerance to aluminum toxicity and good adaptability to the barren acidic soils. All of the 24 EoTIFYs were unevenly located on six out of nine chromosomes and could be classified into two subfamilies (ZIM/ZML and JAZ), consisting of 3 and 21 genes, respectively, with the JAZ subfamily being further divided into five subgroups (JAZ I to JAZ V). The amino acids of 24 EoTIFYs showed apparent differences between the two subfamilies based on the analysis of gene structures and conserved motifs. MCScanX analysis revealed the tandem duplication and segmental duplication of several EoTIFY genes occurred during E. ophiuroides genome evolution. Syntenic analyses of TIFY genes between E. ophiuroides and other five plant species (including A. thaliana, O. sativa, B. distachyon, S. biocolor, and S. italica) provided valuable clues for understanding the potential evolution of the EoTIFY family. qRT-PCR analysis revealed that EoTIFY genes exhibited different spatial expression patterns in different tissues. In addition, the expressions of EoTIFY genes were highly induced by MeJA and all of the EoTIFY family members except for EoJAZ2 displayed upregulated expression by MeJA. Ten EoTIFY genes (EoZML1, EoZML1, EoJAZ1, EoJAZ3, EoJAZ5, EoJAZ6, EoJAZ8, EoJAZ9, EoJAZ10, and EoJAZ21) were observed to be highly expressed under both exogenous MeJA treatment and aluminum stress, respectively. These results suggest that EoTIFY genes play a role in the JA-regulated pathway of plant growth and aluminum resistance as well. The results of this study laid a foundation for further understanding the function of TIFY genes in E. ophiuroides, and provided useful information for future aluminum tolerance related breeding and gene function research in warm-season grass plants.

PSX-12 Effects of Cottonseed Meal Supplementation on Calf Performance and Forage Utilization Grazing Late Season Summer Forage

Abstract Nutritive quality of perennial warm-season grasses during summer may limit the DMI of growing calves due to low protein and increased NDF content. Cottonseed meal (CSM) supplementation may improve forage utilization by increasing rumen degradable protein, but research in calves is limited. It was hypothesized that supplementation of CSM to heifers grazing mature forage would have improved performance due to greater forage DMI and fiber digestibility. Objectives were to compare the effects of CSM supplementation on calf gain performance, estimated forage intake, and in vitro true digestibility (IVTD) and neutral detergent digestibility (IVNDFD) of low-quality, warm-season forage. Angus heifers (n = 18) weighing 232.7 ± 12.6 kg were blocked by BW (light, medium, and heavy) and allocated to 6 paddocks (1.64 ha) of W.W. B-Dahl Bluestem (Bothriochloa bladhii) for 67 d. Heifers were supplemented daily with a mineral mix and either no cottonseed meal (CON) or 454 g/animal of CSM (CSM1) in a RCBD with a 2×3 factorial arrangement of treatments and BW blocks, respectively. Initial and final shrunk BW was measured to calculate total gain, ADG, and percent of BW gained. Forage samples were collected weekly and composited into 3 periods for chemical analysis and in vitro incubations. Forage DMI was estimated using a double sampling technique for each paddock within period. Forage IVTD and IVNDFD were analyzed using batch fermentation with and without CSM in a CRD (2 treatments by 3 periods). Mean forage CP during periods 1 and 2 were 5.75% and increased to 10.3% in period 3 (P &amp;lt; 0.01). Forage NDF content increased over time (64.1 vs. 69.3%; P &amp;lt; 0.01) and estimated forage DMI of heifers tended (P = 0.07) to decrease from 2.9 to 2.1% of BW. Treatment did not affect estimated forage DMI (P = 0.40). Heifers receiving CSM1 gained 28.3% more BW than heifers receiving CON (47.27 vs. 36.82 kg, respectively; P = 0.02). Percent of BW gained was greater for heifers receiving CSM1 than CON (16.9 vs. 13.8% of initial BW, respectively, P = 0.029). There were no treatment by period interactions on IVTD or IVNDFD. The IVTD of forage from period 1 was greater than periods 2 and 3 (49.9 vs. 47.1 and 46.6%, respectively; P = 0.005). The IVTD of forage incubated with CSM tended (P = 0.06) to be greater than forage without CSM (52.1% vs. 47.8%, respectively). The IVNDFD was not affected by period but tended to be greater with CSM inclusion (P = 0.09) relative to CON (24.83% vs. 18.95%, respectively). In conclusion, 454 g/d of CSM supplemented to heifers grazing late-summer W.W. B-Dahl Bluestem forage likely provided sufficient protein to alter ruminal fiber digestibility, without affecting forage intake, and had measurable effects on gain.

Resilience of warm-season (C4) perennial grasses under challenging environmental and management conditions.

Resilience of warm-season (C4) perennial grasses under challenging environmental and management conditions.

Leaf Area Duration and Crop Radiation Use Efficiency Determine Biomass Yield of Lignocellulosic Perennial Grasses under Different Soil Water Content

The aim of the present work was to assess the leaf area duration (LAD) and the radiation use efficiency (RUE) of six warm-season perennial biomass grasses (PBGs) in a two-year field trial in the semiarid Mediterranean climate under different soil water availability. Two ecotypes of giant reed (Arundo donax L., ARCT and ARMO), one ecotype of African fodder cane (Saccharum spontaneum L. subsp. aegyptiacum (Willd.) Hack., SAC) and three hybrids of Miscanthus (the commercial M. × giganteus J.M. Greef, Deuter ex Hodk., Renvoize, M × G, and two new seed-based hybrids, GNT9 and GNT10) were compared under three levels of soil water availability: rainfed, 50% and 100% of maximum crop evapotranspiration (ETm) restoration. The determination of RUE of perennial plants is controversial and has led to contrasting results in past studies. In the present work, LAD and RUE differed among crops and irrigation regimes, being positively affected by supplemental water inputs. SAC, ARCT and ARMO showed both high LAD and RUE, which determined the high biomass yield than both the commercial M × G and the improved Miscanthus hybrids GNT9 and GNT10. RUE was particularly high and less affected by soil water availability during the mid-season, while the effect of irrigation and the differences among the genotypes were larger during the late season. Adequate biomass yield can be achieved by sub-optimal soil water availability, thus reducing the water footprint and increasing the sustainability of these biomass perennial grasses selected for the Mediterranean climate.

Adapting the CROPGRO Perennial Forage model to predict growth and development of Pensacola bahiagrass

Bahiagrass (Paspalum notatum Flüggé) – a warm-season perennial grass – is one of the most important forage species for livestock production in the southeastern United States. Bahiagrass pastures are often managed extensively, without the data and tools necessary for complex management. Crop simulation models have been previously developed for warm-season grasses, enabling forecast of physiological variables and evaluation of various management scenarios. The objective of this study is to calibrate the CROPGRO Perennial Forage model (CROPGRO-PFM) for bahiagrass and to evaluate the performance of the new model across six experimental datasets. Previously developed parameters for the palisadegrass (Brachiaria brizantha cv. Xaraes) model were used initially, followed by modification of parameters more predictive of bahiagrass and its differences from palisadegrass. Major changes included calibration of plant composition, cool season temperature sensitivity, and photoperiod-induced dormancy parameters, corresponding to previous observations of bahiagrass physiology. The final adapted model resulted in effective predictive accuracy for important state variables – harvested herbage mass (RMSE = 729 kg ha−1, d-index = 0.85), above-ground biomass (RMSE = 729 kg ha−1, d-index = 0.82) and crude protein concentration (RMSE = 3.1%, d-index = 0.71). Given the wide range of experimental conditions used for model development, these results suggest that the calibrated CROPGRO-PFM model will be effective for simulating physiological variables across bahiagrass pastoral systems.

111 Forage Mass and Nutritive Value of Cool-Season Grass-Legume Mixtures Overseeded into Bahiagrass Pastures

Abstract Warm-season perennial pastures are the base of livestock production systems in lower Alabama. To overcome the shortage in forage production during the late fall and winter months, during bahiagrass dormancy, overseeding pastures with cool-season annuals can be used as an option for providing forage during this period. Diverse forage mixtures of multiple species and functional groups have gained popularity in use among forage-livestock producers, but few evaluations have been conducted in overseeded sods. The objective of the study was to evaluate forage mass and nutritive value of cool-season forage mixtures overseeded into bahiagrass pastures. Six, 0.40-ha paddocks of ‘Pensacola’ bahiagrass were overseeded with one of three cool-season forage mixtures (n = 2 paddocks/treatment) on November2, 2021: 1) oat (Avena sativa), wheat (Triticum aestivum), and balansa (Trifolium michelianum), red (Trifolium pratense), and white clover (Trifolium repens; ‘clovers’); 2) oat, cereal rye (Secale cereale), and clovers; and 3) cereal rye, annual ryegrass (Lolium multiflorum), and clovers. When forage mixtures reached a target grazing height of 20 cm, paddocks were managed using flash mob stocking with beef cow-calf pairs to graze to a target height of0 cm. Herbage mass, nutritive value, botanical composition and height samples were collected pre- and post-grazing events. There was no treatment (P = 0.240) or treatment × harvest (P = 0.4239) effect on forage mass. Harvest date affected (P = 0.029) forage mass, with greater forage mass at late harvest (1,903.33 kg DM·ha-1) than at early (1,253.33 kg DM·ha-1) in the growing season. There were no treatment effects observed for species components (P &amp;gt; 0.05), although grasses dominated the forage mixtures with an average of 80% grass presence. Legume establishment was poor (less than%) and the remaining species composition consisted of weed species (19%). There was a treatment effect (P = 0.003) on CP, where oat-rye-clovers had the greatest CP and rye-ryegrass-clover had the least CP. Oat-wheat-clover mixtures had greater TDN (79.2%), less NDF (39.8%), and ADF (18.7%) than cereal rye-ryegrass-clover (75.4%, 46.1%, and 22.2% for TDN, NDF, and ADF, respectively), but did not differ from oat-cereal rye-clover mixtures (76.6%, 45.7%, 21.0% for TDN, NDF, and ADF, respectively). In year of this study, overseeding bahiagrass supported forage production over a 2-month period and can be a management tool used to reduce the need for supplementing in the dormancy periods of warm season perennial grasses.

128 Effects of Cottonseed Meal Supplementation Strategy to Stocker Calves Grazing Late Season Summer Forage

Abstract Summer stocker calves grazing perennial warm-season grasses may benefit from protein supplementation due to the low protein content typically observed in these forages. Cottonseed meal (CSM) is an excellent protein supplement that is readily available in the south and is competitively priced per unit of protein in early summer. However, research regarding the effects of CSM supplementation level and frequency on calf gain and composition of gain is limited. It was hypothesized that supplementing CSM to grazing heifers would improve ADG and perhaps alter composition of gain when compared with non-supplemented heifers. Objectives for this experiment were to 1) compare gain and composition of gain between calves supplemented with CSM to non-supplemented calves, and 2) compare the effect of daily vs. alternating days of CSM supplementation. A total of 27 commercial Angus beef heifers weighing 234.1 ± 4.18 kg were blocked by BW (light, medium, and heavy) and allocated to 9 paddocks of W.W. B-Dahl Bluestem (Bothriochloa bladhii) for 67 d. The experimental was designed as a RCBD with 3×3 factorial arrangement of 3 treatments and 3 weight blocks. Heifers were supplemented daily with a mineral mix and either no cottonseed meal (CON), 454 g/animal of CSM daily (CSM1), or 909 g/animal of CSM every other day (CSM2). Initial and final shrunk BW was measured, and total gain, ADG, and percent of BW gained were calculated. Ultrasound of initial and final longissimus muscle area (LMA), backfat (BF), and intramuscular fat (IMF) were measured. There were no treatment by block interactions for any measured variable. Treatment significantly affected total gain and ADG (P = 0.0156), as well as percent of BW gain (P = 0.029). Heifers receiving CSM1 treatment gained 28.3% more total BW than heifers receiving CON (47.27 vs. 36.82 kg, respectively) and CSM2 was intermediate (42.73 kg). Likewise, percent of BW gained was greatest for CSM1 and least for CON (16.9 vs.3.8% of initial BW), with CSM2 not differing (15.5% of initial BW). Treatment did not affect the composition of gain (P ≥ 0.190); however, block tended (P = 0.0812) to affect LMA % gain, with light heifers being greater than medium and heavy heifers (12.00% vs. 7.35% and 5.09% increase, respectively). As expected, heifers grazing late summer W.W. B-Dahl Bluestem forage who received 454 g of CSM daily had significantly greater ADG than heifers not receiving CSM. Heifers receiving 909 g of CSM every other day tended to gain more than heifers not receiving CSM, but replication of this experiment is needed for validation of this specific supplementation strategy. In conclusion, supplementation of CSM to calves grazing low protein summer forage within a limited period may have positive measurable effects on gain.

Evaluation of eastern gamagrass as dual‐purpose complementary bioenergy and forage feedstock to switchgrass

AbstractSwitchgrass (SG) is considered a model bioenergy crop and a warm‐season perennial grass (WSPG) that traditionally served as forage feedstock in the United States. To avoid the sole dependence on SG for bioenergy production, evaluation of other crops to diversify the pool of feedstock is needed. We conducted a 3‐year field experiment evaluating eastern gamagrass (GG), another WSPG, as complementary feedstock to SG in one‐ and two‐cut systems, with or without intercropping with crimson clover or hairy vetch, and under different nitrogen (N) application rates. Our results showed that GG generally produced lower biomass (by 29.5%), theoretical ethanol potential (TEP, by 2.8%), and theoretical ethanol yield (TEY, by 32.9%) than corresponding SG under the same conditions. However, forage quality measures, namely acid detergent fiber (ADF), crude protein (CP), and elements P, K, Ca, and Mg were significantly higher in GG than those in SG. Nitrogen fertilizer significantly enhanced biomass (by 1.54 Mg ha−1), lignin content (by 2.10 g kg−1), and TEY (787.12 L ha−1) in the WSPGs compared to unfertilized treatments. Intercropping with crimson clover or hairy vetch did not significantly increase biomass of the WSPGs, or TEP and TEY in unfertilized plots. This study demonstrated that GG can serve as a complementary crop to SG and could be used as a dual‐purpose crop for bioenergy and forage feedstock in farmers' rotations.

Perennial Warm-Season Grass Forages Impact on Cow-Calf Profitability in the Fescue Belt

Incorporating a perennial warm- season grass (WSG) into tall fescue (Lolium arundina-ceum [Schreb.] Darbysh.) forage systems in the fescue belt can help avoid the effects of fescue toxicosis on beef cattle (Bos taurus) reproduction and animal performance and provide forage during summer when fescue production is low. However, little information is available on the economics of incorporating WSG into fescue-based forage systems. We developed a simulation model to compare profitability of three forage systems—100% tall fescue, 70% tall fescue/30% bermudagrass (Cynodon dactylon), and 70% tall fescue/ 30% switchgrass (Panicum virgatum)—while also comparing spring- and fall-calving sea-sons on model beef cattle cow-calf operations in the fescue belt. Incorporating switch-grass increased profitability of tall fescue forage systems in both spring- and fall- calving herds, while adding bermudagrass increased profitability in spring-calving herds but not fall-calving herds. Spring-calving herds benefited the most from incorporating WSG, with profitability increases of $877 and $372 per hectare for switchgrass and bermudagrass, respectively, over the 100% tall fescue system. The order of profitability of forage systems did not change with randomly simulated decreases in rainfall and associated increased hay- feeding days, but with annual rainfall >88% of the long- term average, fall- calving 100% tall fescue was more profitable than fall- calving 70% tall fescue/30% bermuda grass. Of the scenarios modeled, the results of the simulation suggest that a profit-maximizing producer would utilize a 70% tall fescue/30% switchgrass forage system.

198 Using Annual Forage Crops to Extend Grazing: What are the Benefits to Production and Livestock Enterprise Economics

Abstract Extending the grazing season, and thereby reducing reliance on harvested and stored forages, positively affects the economics of grazing livestock. In the Southern Great Plains and Southeastern regions of the U. S., grazing systems are dominated by warm season perennial grasses. The most famous example of using annual forages to extend the grazing season in the Southern Great Plains is the use of wheat (and other cool-season annuals) in crop fields as a forage resource during the winter and early spring in either dual purpose (grazing and grain production) or graze-out (grazing entire crop) uses. Even in foraging systems that utilize both warm-season perennials and cool-season annuals in the Southern Great Plains, a substantial forage shortfall occurs in late summer and early fall. In the Northern Great Plains, native and perennial introduced forage species are primarily cool-season species, but still have primary productivity during late spring and summer, with production shortfalls during early winter and spring. While in the Mid-West, predominantly cool-season perennial pastures have production shortfalls and reduced forage nutritive value in mid-summer, commonly known as ‘summer slump’. In any and all of these environments, annual forages can and have been used to fill gaps in forage production. Recent research has investigated using annual forages in novel ways to further extend grazing seasons. In the northern Midwest summer plantings of cool season annuals such as oats have been used to provide grazing resources during the fall and early winter. While in the southeast, late summer plantings of warm-season annuals have filled the fall forage gaps. Annual forages offer many advantages in designing systems to extend grazing seasons in all environments. Annual forages are generally higher in nutritive value than perennials and plantings can be timed to fill gaps in availability of the dominant perennial forages in the local environment.

Comparison of Nutritive Values of Tropical Pasture Species Grown in Different Environments, and Implications for Livestock Methane Production: A Meta-Analysis.

Simple SummaryGlobally, tropical pasture species predominate in tropical and subtropical climates, and are the primary feed source for grazing livestock including dairy cattle. Therefore, this study aimed at systematically analysing the nutritive values of tropical pastures and the implications of potential methane gas production from tropical pasture species and livestock, in relation to the growing conditions and agronomic management approaches used (defoliation frequency and intensity) across different climates. This analysis allowed us to understand the better performing tropical pasture species grown across wider geographical regions, in order to improve pasture-based livestock production systems. Results revealed that pasture quality and methane gas production varied among and within species, and were significantly affected by the climate and by the agronomic management regime as well.The demand for dairy products is ever increasing across the world. The livestock sector is a significant source of greenhouse gas (GHG) emissions globally. The availability of high-quality pasture is a key requirement to increase the productivity of dairy cows as well as manage enteric methane emissions. Warm-season perennial grasses are the dominant forages in tropical and subtropical regions, and thus exploring their nutritive characteristics is imperative in the effort to improve dairy productivity. Therefore, we have collated a database containing a total of 4750 records, with 1277 measurements of nutritive values representing 56 tropical pasture species and hybrid cultivars grown in 26 different locations in 16 countries; this was done in order to compare the nutritive values and GHG production across different forage species, climatic zones, and defoliation management regimes. Average edaphoclimatic (with minimum and maximum values) conditions for tropical pasture species growing environments were characterized as 22.5 °C temperature (range 17.5–29.30 °C), 1253.9 mm rainfall (range 104.5–3390.0 mm), 582.6 m elevation (range 15–2393 m), and a soil pH of 5.6 (range 4.6–7.0). The data revealed spatial variability in nutritive metrics across bioclimatic zones and between and within species. The ranges of these nutrients were as follows: neutral detergent fibre (NDF) 50.9–79.8%, acid detergent fibre (ADF) 24.7–57.4%, crude protein (CP) 2.1–21.1%, dry matter (DM) digestibility 30.2–70.1%, metabolisable energy (ME)3.4–9.7 MJ kg−1 DM, with methane (CH4) production at 132.9–133.3 g animal−1 day−1. The arid/dry zone recorded the highest DM yield, with decreased CP and high fibre components and minerals. Furthermore, the data revealed that climate, defoliation frequency and intensity, in addition to their interactions, have a significant effect on tropical pasture nutritive values and CH4 production. Overall, hybrid and newer tropical cultivars performed well across different climates, with small variations in herbage quality. The current study revealed important factors that affect pasture nutritive values and CH4 emissions, with the potential for improving tropical forage through the selection and management of pasture species.

Evaluation of harvest time effects on the combustion quality of warm- and cool-season perennial grasses in two contrasting semi-arid environments

In order to achieve economically viable and sustainable solid biofuel production from perennial grasses, high biomass productivity must be complemented by good combustion quality. The aim of this research was to compare the combustion quality of 7 cool-season perennial grasses, comprising bulbous canary grass, reed canary grass, smooth brome grass, orchard grass, tall wheatgrass, tall fescue, and perennial ryegrass, and 3 warm-season perennial grasses, comprising switchgrass, miscanthus, and giant reed, over 2 harvest times (autumn, winter/early spring) in 2 contrasting semi-arid environments (Adana, and Cankiri, Turkey). Delaying the harvest from the autumn to the winter or the spring significantly increased the lignin contents of each of the 3 warm-season grasses and generally decreased the contents of all of the minerals, except for Al and Fe, in miscanthus and switchgrass, and K and Na in giant reed, at both locations. Similar trends were also generally observed for all of the cool-season grasses, except for the orchard grass that was grown in Cankiri. Additionally, delayed harvest resulted in lower slagging tendency and sintering risk in all of the perennial grass species, except for giant reed in Cankiri. However, the autumn harvest caused significantly higher lignin, but generally lower N, P, K, Ca, S, Si, Al, and Fe contents, slagging tendency, and sintering risk in most of the cool-season grasses that were grown in Adana. On the other hand, despite the autumn harvest in Adana, and the spring harvest in Cankiri provided a substantial improvement in combustion quality of the cool-season grasses, mainly due to the reduced mineral and increased lignin contents, they still exhibited relatively lower combustion quality than miscanthus and switchgrass, especially in Adana. These results showed that further effort is needed to improve the combustion quality of cool-season grasses in order for them to be primary biomass feedstock alternatives for dry marginal lands of semi-arid environments.

Tissue Culture and Somatic Embryogenesis in Warm-Season Grasses-Current Status and Its Applications: A Review.

Warm-season grasses are C4 plants and have a high capacity for biomass productivity. These grasses are utilized in many agricultural production systems with their greatest value as feeds for livestock, bioethanol, and turf. However, many important warm-season perennial grasses multiply either by vegetative propagation or form their seeds by an asexual mode of reproduction called apomixis. Therefore, the improvement of these grasses by conventional breeding is difficult and is dependent on the availability of natural genetic variation and its manipulation through breeding and selection. Recent studies have indicated that plant tissue culture system through somatic embryogenesis complements and could further develop conventional breeding programs by micropropagation, somaclonal variation, somatic hybridization, genetic transformation, and genome editing. This review summarizes the tissue culture and somatic embryogenesis in warm-season grasses and focus on current status and above applications including the author’s progress.

Biology and Management of Johnsongrass (Sorghum halepense) in Ornamental Crop Production and Landscapes

Johnsongrass is a warm-season perennial grass and one of the most persistent and troublesome weeds in the southern United States. This new 5-page publication of the UF/IFAS Environmental Horticulture Department was developed to help commercial nursery growers, landscapers, and other green industry professionals identify and manage johnsongrass. Written by Ping Yu, Ernest Kraka, and Chris Marble.https://edis.ifas.ufl.edu/ep620